Controlled release of antihypertensive drug from the interpenetrating network poly(vinyl alcohol)-guar gum hydrogel microspheres

Poly(vinyl alcohol)-guar gum interpenetrating network microspheres were pre pared by cross-linking with glutaraldehyde. Nifedipine, an antihypertesive drug, was loaded into these matrices before and after cross-linking to stud y its release patterns. The extent of cross-linking was analyzed by Fourier transform infrared spectroscopy and differential scanning calorimetry. Fur thermore, the microspheres were characterized for drug entrapment efficienc y, particle size, transport of water into the matrix and drug release kinet ics. Scanning electron microscopic photographs confirmed the spherical natu re and surface morphology. The mean particle size of the microspheres was f ound to be around 300 mu m. The molecular transport phenomenon, as studied by the dynamic swelling experiments. indicated that an increase in cross-li nking affected the transport mechanism from Fickian to non-Fickian. The in vitro release study indicated that the release from these microspheres is n ot only dependent upon the extent of cross-linking, but also on the amount of the drug loaded as well as the method of drug loading.